Aircraft design is an inherently multidisciplinary activity that requires integrating different models and tools to reach a well-balanced and optimized product. At Linköping University a design framework is being developed to support the initial design space exploration and the conceptual design phase. Main characteristics of the framework are its flexible database in XML format, together with close integration of automated CAD and other tools, which allows the developed geometry to be directly used in the subsequent preliminary design phase. In particular, the aim of the proposed work is to test the framework by designing, optimizing and studying a transport aircraft wing with respect to aerodynamic, geometry, structural and accessability constraints. The project will provide an initial assessment of the capability of the framework, both in terms of processing speed and accuracy of the results.

A suitable method for simulating large complex dynamic systems is represented by distributed modelling using transmission line elements. The method is applicable to all physical systems, such as mechanical, electrical and pneumatics, but is particularly well suited to simulate systems where wave propagation is an important issue, for instance hydraulic systems. By using this method, components can be numerically isolated from each other, which provide highly robust numerical properties. It also enables the use of multi-core architecture since a system model can be composed by distributed simulations of subsystems on different processor cores.

Technologies based on transmission lines has successfully been implemented in the HOPSAN simulation package, develop at Linköping University. Currently, the next generation of HOPSAN is developed using an object-oriented approach. The work is focused on compatibility, execution speed and real-time simulation in order to facilitate hardware-in-the-loop applications. This paper presents the work progress and some possible features in the new version of the HOPSAN simulation package.

Purpose - The purpose of this paper is to present the latest subscale demonstrator aircraft developed at Linkoping University. It has been built as part of a study initiated by the Swedish Material Board (FMV) on a Generic Future Fighter aircraft. The paper will cover different aspects of the performed work: from paper study realised by SAAB to the first flight of the scaled demonstrator. The intention of the paper is to describe what has been realised and explain how the work is may be used to fit within aircraft conceptual design. Design/methodology/approach - The approach has been to address the challenges proposed by the customer of the demonstrator, how to design, manufacture and operate a scaled demonstrator of an aircraft study in conceptual design within five months. Similar research projects have been reviewed in order to perform the current work. Findings - The results obtained so far have led to new questions. In particular, the project indicated that more research is needed within the area of subscale flight testing for usage in aircraft conceptual design, since a scaled demonstrator is likely to answer some questions but will probably open up new ones. Research limitations/implications - The current research is just in its infancy and does not bring any final conclusion but does, however, offer several guidelines for future works. Since the aircraft study was an early phase concept study, not much data are available for validation or comparison. Therefore, the paper is not presenting new methods or general conclusions. Practical implications - Results from a conceptual aircraft study and a realisation of a scaled prototype are presented, which show that scaled flight testing may be used with some restriction in conceptual design. Originality/value - The value of this paper is to show that universities can be involved in prototype development and can work in close collaboration with industries to address issues and solutions within aircraft conceptual design.

A new fighter aircraft will most likely be acollaborative project. In this study conceptualknowledge-based design is demonstrated, usingmodels of comparable fidelity for sizing, geometrydesign, aerodynamic analysis and system simulationfor aircraft conceptual design. A newgeneration fighter is likely to involve advancedcontrol concept where an assessment of feasibilitythrough simulation is needed already atthe conceptual stage. This co-design leads to adeeper understanding of the trade-offs involved.In this paper a study for a future combat aircraftis made. Conceptual knowledge-based design isdemonstrated by optimizing for a design mission,including a super-cruise segment.

"The conceptual design is the early stage of aircraft design process where results are needed fast, both analytically and visually so that the design can be analyzed and eventually improved in the initial phases. Although there is no necessity for a CAD model from the very beginning of the design process, it can be an added advantage to have the model to get the impression and appearance. Furthermore, this means that a seamless transition into preliminary design is achieved since the CAD model can guardedly be made more detailed. For this purpose, knowledge-based aircraft conceptual design applications Tango (Matlab) and RAPID (CATIA) are being developed at Linköping University. Based on a parametric data definition in XML, this approach allows for a full 3D CAD integration. The one-database approach, also explored by many research organizations, enables the flexible and efficient integration of the different multidisciplinary processes during the whole conceptual design phase. This paper describes the knowledge-based design automated methodology of RAPID, data processing between RAPID and Tango and its application in the courses ‘‘Aircraft conceptual design’’ and ‘‘Aircraft project course’’ at Linköping University. A multifaceted user interface is developed to assist the whole design process."

This paper describes the XML basedmultidisciplinary tool integration in aconceptual aircraft design framework,developed by the Division of Fluid andMechatronic Systems (FluMeS), LinköpingUniversity. Based on a parametric datadefinition in XML, this approach allows for afull 3D CAD integration. The one-databaseapproach, also conducted by many researchorganizations, enables the flexible and efficientintegration of the different multidisciplinaryprocesses during the whole conceptual designphase. This central database approach with adetailed explanation of the developed geometrydescription and the data processing, focusing onthe CAD integration is presented. Applicationexamples of the framework are presentedshowing the data build up and data handling.

This paper looks at fuel consumption due to shaft power off-takes from the engine and the related increase in the aircraft’s fuel consumption. It presents a review and comparison of published and unpublished data on this kind of consumption. The paper presents results from the TURBOMATCH engine simulation model, calibrated to real world engine data. A generic equation is derived for the calculation of fuel consumption due to shaft power extraction. Main result is the shaft power factor kP found to be in the order of 0.002 N/W for a typical cruise flight. This yields an amazingly high efficiency for power generation by shaft power extraction from a turbo fan engine of more than 70 %.

This paper presents the development of a design framework for the initial conceptual design phase. The focus in this project is on a flexible database in XML format, together with close integration of automated CAD, and other tools, which allows the developed geometry to be used directly in the subsequent preliminary design phase. The database and the geometry are also described and an overview is given of included tools like aerodynamic analysis and weight estimation.

Model management during conceptual aircraftdesign is an important issue. This paper showsthe basic ideas and capabilities of the conceptualaircraft design framework developed atLinköping University with focus on efficient lowfidelity geometry definition. As an example, theanalysis of an F-16 fighter is presented.

This paper describes the development of a scalable simulation model of a bleed-less, fully electric Environmental Control System (ECS). The focus during development of the model was on fast execution speed and system architecture in order to enable optimization algorithms for system efficiency optimization to be constructed. Classical sensitivity and robustness analysis were used during model development. ECS architecture functionality and reliability has been proven for different flight mission working conditions as well as different failure modes. For this purpose, an analysis tool related to the simulation model and active simulation model control was developed.

This paper describes the methodology of generating simulation models out of basic information, available during conceptual design phase. The implementation of an aircraft system is shown as an example using the simulation software HOPSAN.

Because of the limited direct project-related data available at the conceptual stage, the traditional method of creating physical simulation models by the bottom up approach with the help of (standard) component libraries is not applicable. Instead, the respective systems’ architecture as well as their composition has to be descriptively predefined in a flexible, wide-range applicable manner, known as the knowledge base (KB) approach. These system technology driven design declarations – combined with project related data – result in roughly pre-tuned system simulation models, which may help when conducting more detailed investigations of the project such as performance analysis.

This (system architecture) knowledge-based approach is shown on the whole aircraft system level down to the detailed implementation of the control surface actuator systems of the primary flight control system.

At Linkoping University aeronautical research is focusing on design methodologies in early stages of aircraft design. Rapid design and evaluation of prototypes is considered an important branch of this work. In this paper flight test activities at the university are described, the design of a light weight affordable data acquisition system is explained and some flight test results including flow visualization are presented.